Last time I wrote an article for providing Facebook Sign-In using Clojure. This article will guide you to add Google Sign-In functionality in your web application using clojure. We’ll use compojure.core for routing, clj-http.client for http requests, cheshire.core for parsing json and noir.response for redirections.

“red” defines the request url on which the user is redirected to ask for user permission for user details. We use ring.util.codec/url-encode to encode the url details. ring.util.codec/url-encode uses UTF-8 encoding by default.

Define routes in “google” namespace in order to redirect a user to the url defined by “red” as follows:

(defroutes google-routes
(GET "/google" [] (resp/redirect red)))

After user provides permission to your google project, you will get an authorization code on the the redirect uri that you mentioned in your google project, the same that you defined in your namespace, i.e http://localhost:3000/auth_google.

Now define a new route in google-routes as:

(GET "/auth_google" {params :query-params}
(google params))

and a new function in order to get the access code and user details as:

In the above function we use clj-http’s “post” to make a post request to get access token followed by “get” to get user information. Then we use cheshire.core’s “parse-string” to parse json response and convert it into clojure object and save the information in the atom defined as “google-user”.